Anemia/cell inclusions/parasites Flashcards
anemia
absolute decrease in PCV, Hg concentration, and/or RBC count
clinical sign of disease, not a diagnosis
MCV in anemia
mean corpuscular volume, RBC size
normocytic, macrocytic, microcytic
MCHC in anemia
mean corpuscular hemoglobin concentration, Hg concentration
normochromic or hypochromic
how is anemia classified?
by RBC size and Hg concentration
then we look at bone marrow response and see if we have certain mechanisms occurring that are causing anemia
causes of anemia
blood loss/hemorrhage
this can happen from trauma, surgery, GI ulcers, hemostatic defects (DIC, rodenticide, sweet clover toxicosis), parasitism, neoplasia, vitamin K deficiency
possible clinical signs of anemia
tachycardia, tachypnea
what happens in the body as anemia sets in?
PCV is initially within reference range because all blood components will be equally lost (plasma and cells)
splenic contraction occurs as body starts to try to compensate
interstitial fluids shift in and out of cells to try to increase BP and blood volume, this dilutes red cell mass = PCV, Hg, RBC count decreases = anemia, low protein
how are signs of anemia seen in chronic blood loss?
slower signs of anemia because the body adapts
RBC indices
MCV, MCH, MCHC, RDW
RDW = red cell distribution width: variation in size and volume
hemolysis (IMHA)
hallmarks: spherocytosis, autoagglutination, positive Coombs test (antibodies against RBCs)
hemolysis is usually immune mediated but can be caused by toxins or infections
reduced/defective erythropoiesis
can be caused by bone marrow damage, neoplasia, chronic renal disease, or infection
bone marrow damage reduced/defective erythropoiesis signs
non-regenerative anemia and pancytopenia (granulocytes affected first, then platelets, then RBCs)
neoplasia caused reduced/defective erythropoiesis
caused by blood loss from bleeding tumors or effects on bone marrow
which infections can cause reduced/defective erythropoiesis?
Ehrlichia, FeLV, feline panleukopenia, parvo
regenerative anemia
bone marrow responding to demand
increased MCV (macrocytosis or anisocytosis), basophilic erythrocytes, higher amount of RNA released from bone marrow with lower number of reticuloytes
retic count
polychromatophils in NMB
cats: only count aggregate
reticulocytosis = regenerative anemia
basophilic stippling
punctate aggregates of RNA
shows regeneration in bovids
dogs/cats: basophilic stippling but minimal polychromasia could be lead toxicity (> 10 nRBCs/100 cell diff)
aggregate vs punctate
aggregate is like clumps of residual RNA
punctate is like little dots of RNA, aggregate broken up, aka basophilic stippling
punctate more mature
how do you perform a retic count?
- mix together fresh blood and NMB
- incubate for at least 15 minutes
- make a blood smear
- look under microscope to obtain % of retics in 10 fields (# of retics divided by 1000 multiplied by 100)
what is the one animal you can’t do a retic count for?
horses because they don’t release retics from the bone marrow
maturation is confined to bone marrow
how do you calculate corrected retic count?
retic % times observed PCV/HCT divided by normal PCV/HCT
what is the normal PCV/HCT in dogs and cats?
dogs: 45%
cats: 37%
how do you calculate absolute retic count?
retic % (converted to a decimal) times total RBC count/uL
reticulocyte production idex (RPI)
usually used in human med, can only be applied to dogs because we have lack of information for other species
corrected retic % divided by maturation time based on observed HCT
retic maturation index
HCT: 45% = 1x faster maturation
HCT: 35% = 1.4x faster maturation
HCT: 25% = 2x faster maturation
HCT: 15% = 2.5x faster maturation
polycythemia
increased circulating RBCs
causes: relative or absolute
relative polycythemia
dehydration cause
most common polycythemia
will have increased TP and HCT as well
absolute polycythemia
true polycythemia
1. primary: polycythemia vera = very rare, dogs/cats may have RBC population of 65-75%, blood becomes thick and has difficulty moving through small vessels = fewer nutrients and O2 delivered, animals feel tired, sluggish, weak, seizures
2. secondary: compensatory response (appropriate response) = body responding to reduced oxygenation of tissues, usually compensating for heart disease or pneumonia
3. inappropriate response = renal disease, kidneys can cause increased erythropoietin release
Howell-Jolly bodies
nuclear remnants
normal in low numbers in cats and horses
sign of regenerative anemia
seen in animals that had a splenectomy since the spleen removes these normally
heinz bodies
cats most common
round angular retractile bodies - confirm on NMB
denatured Hg
caused by toxicity: onions, acetaminophen, propylene glycol
disease causing: diabetes mellitus, hyperthyroidism
40% of cats with increased amounts is usually from metabolic disease: diabetes, pancreatitis (ketones damaging Hg) “old cat dz”
eccentrocytes
hemoglobin pushed to the side
same as heinz bodies
barr body
pyknotic inactive remains of 1 of the 2 X chromosomes
low numbers seen in neutrophils of normal female animals
Babesia canis
protozoan hemoparasite
large form
tick vector
affects large animals
causes hemolytic anemia
pear shaped droplets or pyramid shaped with pinpoint magenta center
Babesia gibsoni
protozoan hemoparasite
cignet ring shape, harder to see than Babesia canis
common in US
causes hemolytic anemia and thrombocytopenia
small form
very serious strain in pit bulls and greyhounds through bites (breeds used for racing/fighting)
bites or vertical transmission
PCR testing available
single, paired, or tetrad oval inclusions usually on feathered edge
piroplasmosis
protozoan hemoparasite
seen in equids: horses, donkeys, zebras
tick vector
USDA reportable
we are free of this disease
50% mortality
cytauxzoon felis
protozoan hemoparasite
tick transmission: commonly lone star tick
causes non-regenerative hemolytic anemia: usually thrombosis will cause fatality, some virulence variability (some survival in Arkansas cats unexplained)
fatal
same look as small form babesia
bobcat reservoir host
infection more likely in cats not receiving prophylaxis
PCR testing available
cytauxzoon felis CS
reduced appetite, followed rapidly by anorexia, lethargy, sometimes vocalization (interpreted to be pain or discomfort)
usually see pronounced fever
hepatazoon
protozoan hemoparasite
affects WBCs
classified as H. americanum: causes severe disease
American canine hepatazoonosis (ACH): causes mild disease in other areas of world
ACH is an EID (emerging infectious disease): severe disease in Gulf Coast
caused by ingestion of infected ticks
fatal if untreated
gamonts = large oblong structure displaces nucleus
hemoproteus
RBC protozoan of wild birds
“hugs” RBC nucleus
CS vary by species
frequently causes fatalities in pigeons and doves
leucocytozoon
protozoan infects RBC and WBC
distorts cell “loco”: gametocytes distort host cell elongating and distending cell
arthropod vector
causes mild to severe anemia
plasmodium
protozoan hemoparasite
avian malaria
“pushy sausage” (displaces RBC nucleus)
mosquito vector
causes anemia
related species causes disease in reptiles, mammals, humans in tropical areas
gametes in RBC cause nuclear displacement
hemogregarines
protozoan hemoparasite
affects RBCs
affects reptiles especially snakes
sausage shaped gametes in cytoplasm of RBCs which displaces nucleus
usually non-pathogenic but increased stress can increase infection and cause mortality
trypanasomes
protozoan hemoparasite
seen in tropics: sleeping sickness
elongated, flagellated protozoans
extracellular
cattle, sheep, wild birds, reptiles, fish affected
pathogenic and non-pathogenic strains (usually non-pathogenic in US)
Chagas (American trypanosomiasis): T. cruzi: seen in the South
zoonotic
transmitted by kissing bug or eating infected bugs/rodents
causes heart failure
hemotrophic mycoplasma
bacteria hemoparasite
hemofelis/hemocanis
hemobartonella
arthropod vector (fleas), vertical or direct transmission
can detach from RBC: PCR test
cocci-like: smallest free-living microorganism
dogs don’t typically develop disease unless they had a splenectomy
huge variety: some can infect humans, only some cause clinical illness but seeing more outbreaks in sheep, cattle, pigs
causes agglutination/IMHA in symptomatic animals and mild to fatal anemia in cats (feline infectious anemia: FIA)
anaplasma
bacteria hemoparasite
looks like mycoplasma
high prevalence in cattle globally: A. marginale
tickborne
causes fatal hemolytic anemia
dogs responsive to treatment of antibiotics or can be asymptomatic
up to 50% mortality
rickettsial
somewhere between bacteria and virus
ehrlichia canis
rickettsial hemoparasite
one of the most common blood parasites in small animals
affects neutrophils during acute infection and then moves into monocytes
tick transmission: Rhipicephalus (brown dog tick)
packets of morulae (bacterial organisms) seen in RBCs
can affect dogs, horses, llama, cats
CS: thrombocytopenia, fever, lethargy, renal failure
distemper
viral
variable in size and stain pink to light purple
highly contagious, widespread throughout US in wild carnivores
microfilaria (dirofilaria)
extracellular
large!
round head and tapered tail
dark purple stippled internal organs
